1. Field
The invention is related to an apparatus and method for preventing the filling compound (gel) optical fiber from ejecting, flowing or protruding out of buffer tubes in fiber optic cables.
2. Related Art
Many utilities, city municipals and telephone companies deploy systems that use fiber optic cable. Many fiber optic cables contain buffer tubes that are manufactured with a filling compound (gel). The purpose of the gel is to protect the fibers and act as a water blocking agent to prevent water from tracking into the buffer tubes and damaging the fibers and or fiber performance. Three of the typical types of cables used are: OPGW: Optical Ground Wire uses both plastic and or stainless steel buffer tubes (Aerial applications); ADSS: All Dielectric Self Supporting cable containing plastic buffer tubes (Aerial applications); and Loose Tube: Multiple cable designs containing plastic buffer tubes (Non-aerial applications).
Buffer tubes contain a filling compound that allows the fibers to float within the tube. The gel also helps allow the buffer tubes to store an, excess fiber length or “EFL.” EFL is the term used when talking about the length of the fiber within the buffer tube compared to the actual length of the buffer tube. The excess length of fiber within the tube helps determine the point at which the fiber will see strain. The fiber optic cables are typically installed and terminated within a splice enclosure. The splice enclosure is used to help protect the exposed fibers and buffer tubes from all types of elements. An AFL Telecommunications “SB01” splice enclosure is a good example of an enclosure that is used in an aerial application.
After the fiber optic cable has been secured within the splice enclosure, the buffer tubes are routed within the enclosure and the fibers are then terminated (spliced) within a fiber optic splice tray.
Fiber optic cable may be deployed in several harsh or non-standard environments world wide. Two such environments are Extreme Heat and Vertical Installations. In rare applications, optical fiber may migrate or flow out the ends of the buffer tubes. The issue is not typical but can occur due to the viscosity of the filling compound (gel), amount of fibers within the buffer tube versus the inner diameter, vertical installation length and extreme or sustained temperatures while in a vertical position. If a fiber optic product shows signs of migration, the gel and fiber will begin to push its way into the splice enclosure and tray. The end result for this action can be the loss of EFL, bending, kinking or breaking of optical fibers and a possible overall failure to the optical system.
Due to the abundance of fiber optic cable being installed world wide for communications needs, it has become extremely important to maintain and protect the functionally of our fiber optic networks. For this reason, it is vitally important to have a product and procedure in place that will prevent the filling compound and optical fibers from migrating out of the buffer tubes.